title: In vitro susceptibility of selected isolates of Brucella abortus to penicillin.
abstract: Brucella abortus isolates (n = 134) from 38 dairy herds in Vermont, Florida, and Canada exhibited 2 growth patterns on medium containing 5 U of penicillin/ml. The B abortus isolates from 7 herds in Vermont were always susceptible to the antibiotic at that concentration. Eleven of 12 isolates from 1 herd in Florida and 25 isolates (biotypes 1 and 4) from 30 Canadian herds grew at greater than or equal to 5 U of penicillin/ml, as determined using a gradient plate method. Penicillin susceptibility may be of value in identifying the source of infections in cattle.
mesh_terms: D000818:Animals; D002003:Brucella abortus / Q000145:classification* / Q000187:drug effects; D002170:Canada; D002417:Cattle / Q000382:microbiology; D005431:Florida; D010403:Penicillin Resistance; D010406:Penicillins / Q000494:pharmacology*; D014707:Vermont
chemical_list: D010406:Penicillins